Combine appropriate test levels
Unit tests check focused rules; integration tests check how services work together; end-to-end tests exercise complete user journeys. Include permissions, poor connectivity and server errors where relevant. Automate checks that protect important behaviour and use manual investigation for interactions that automated scripts cannot assess reliably.
Validate with real devices and users
Test representative devices and supported operating systems. Check accessibility, text resizing, keyboards and interruptions. Beta distribution allows a broader group to exercise the product before a public release. Observe the actual experience and document defects clearly so that the team can reproduce and prioritise them.
Use explicit acceptance criteria
Agree which journeys and requirements must pass before release. Separate blocking defects from later improvements and assign responsibility for retesting. API simulations can validate interface recovery, but they do not prove the production service works. Complete appropriate integration and operational checks before relying on the app for real customer activity.